Many people use mobile stations, such as cell phones and personal digital assistants (PDAs), to communicate with cellular wireless networks. These mobile stations and networks typically communicate with each other over a radio frequency (RF) air interface according to a wireless protocol such as Code Division Multiple Access (CDMA), perhaps in conformance with one or more industry specifications such as IS-95 and IS-2000. Wireless networks that operate according to these specifications are often referred to as “1xRTT networks” (or “1x networks” for short), which stands for “Single Carrier Radio Transmission Technology.” Another CDMA protocol that may be used is known as Evolution Data Optimized (EV-DO), perhaps in conformance with one or more industry specifications such as IS-856, Rel. 0 and IS-856, Rev. A. Other protocols may be used as well, such as Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), WiMax, and/or any others.
These networks typically provide services such as voice, Short Message Service (SMS) messaging, and packet-data communication, among others, and typically include a plurality of base stations, each of which provide one or more coverage areas, such as cells and sectors. These base stations are typically not associated with any subscriber or small group of subscribers in particular; rather, they are placed in publicly-accessible locations and are used by the service provider's customers generally, and their coverage areas collectively blanket cities, rural areas, etc. When a mobile station is positioned in one of these coverage areas, it can communicate over the air interface with the base station, and in turn over one or more circuit-switched and/or packet-switched signaling and/or transport networks to which the base station provides access. In such an arrangement, the base-station-to-mobile-station link is known as the forward link, while the mobile-station-to-base-station link is known as the reverse link.
When a mobile station seeks to, as examples, originate a communication session (e.g. a voice call) or respond to a page message from a base station, the mobile station sends one or more messages known as access probes to the base station over a reverse-link access channel. As part of this process, the mobile station determines a transmit power level at which to send communications to the base station.
More specifically, to arrive at an appropriate transmit power for communications, a mobile station typically determines an initial transmit power at which to send an initial access probe, and then transmits an access probe at the initial transmit power. If the base station does not acknowledge the initial access probe, the mobile station then re-transmits the access probe at an incrementally higher power level (e.g. 3 dB higher than the previous access probe). The mobile station repeats this process (i.e. incrementally increasing the power level and re-transmitting) until either receiving an acknowledgement from the base station or reaching a set number (e.g. five) of transmitted access probes. The mobile station may then wait a timeout period, and start again at the initial transmit power. The mobile station may repeat this entire cycle a set number of times (e.g. three) before concluding that the base station is not reachable, or perhaps waiting a longer timeout period before starting the entire sequence over. And other variations on this access-probe-sending sequence exist as well, as this description is merely an example.